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I am building a single DC power supply from scratch. I use the transformer to step down the 120 volts wall line. I want to use a non center tapped transformer. I found a center tapped transformer (one that has 3 connectors on the secondary side).

I just want to ignore the middle one and treat it as a non center tapped transformer.

Is this possible to do? just simply ignore the middle connector? What are the "product-wise" consequences of being me ignoring this middle connector? I mean, in my schematic, it will appear as a non tapped transformer, but in reality, the product may behave in an unexpectable and unacceptable way? I am worried about this.

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    \$\begingroup\$ People ignore the center tap all the time. There shouldn't be any additional consequences for ignoring the center tap. Some transformers (good ones, often) set things up so you have two secondaries where you can tie them together in series to double the voltage or in parallel to double the supported current. \$\endgroup\$ – jonk Oct 9 '16 at 1:37
  • \$\begingroup\$ Just ignore the centertap - but if it is a wire rather than a terminal on the transformer, insulate the end of the wire so it won't short to anything. \$\endgroup\$ – Peter Bennett Oct 9 '16 at 1:59
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schematic

simulate this circuit – Schematic created using CircuitLab

Figure 1. The schematic symbols for the regular transformer and centre-tapped version hint that they are the same except for the tap.

One could tap off in multiple places on the secondary coil without affecting the end to end voltage.

Is this possible to do - just simply ignore the middle connector?

Certainly.

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Simply ignore the center tap -- it does nothing if you leave it open circuit. (If your transformer has wire leads, make sure to insulate the loose end so it doesn't short to something.)

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If there are only THREE terminals on the secondary (output) side of the transformer, then YES, you can safely ignore the center-tap.

HOWEVER, note that many transformers have "split" secondary windings where you can connect the windings in series for "double" the voltage and "half" the current. Or you can connect them in parallel for double the current and half the voltage. So, if your transformer had more than 3 output terminals, you would likely have to connect the windings in series.

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